Abstract: According to the question of cloud drop weight in the existing trust model based on cloud model,a new trust evaluation model based on trust cloud is proposed.Credibility of evaluation data is estimated according to evaluation number and evaluation consistency of the feedback entity;History evaluation data is regard as the quantitative universe of discourse;Trust cloud of entities' property is based on the weighted backward generation cloud algorithm;uncertainty factor of the evaluated entity and laterality factor of the buyer entity are introduced for trust decision-making at last.Simulation and analysis show that the model proposed in the paper can reflect a seller's property more accurately and can provide a favorable reference for a buyer entity in e-commerce.